2021-12-08_GENERAL DOCUMENTS - C1981019

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DocuSign Envelope ID:6BC32598-B737-464E-898A-81 F1 F7131339133 where R' is fluid front radius including dispersion, R is the fluid front radius determined from the volumetric method, and D is the dispersion coefficient. Mechanical dispersion is generally not a directly measured parameter, and a rule of thumb value on the order of 10 percent of the travel distance is typically applied. Assuming a dispersion coefficient of 30 feet and the non-dispersion fluid front radius determined previously, Equation A-2 resulted in a fluid front radius with dispersion of 486 feet. At the proposed UIC location approximately 70' of Mancos shale exists between the top of the injection zone and the base of the Iles Formation, and approximately 520' of mostly shales exists between the top of the injection zone and the completed interval in well Taylor Creek#3 in the Iles Formation. No geologic faults have been identified in the immediate area. An inferred and queried fault is shown on the Colorado Geological Survey's (CGS) Geologic Map of the Axial Quadrangle; however, this fault is located on the opposite side of the Collom Syncline from the proposed injection well and outside the calculated fluid front radius. The only identified potential conduits by which fluids could migrate to a USDW would be existing boreholes or fractures induced by exceeding breakdown pressure at the injection well. All oil and gas wells in the COGCC database within a 5-mile radius of the proposed UIC location are listed as plugged and abandoned, drilled and abandoned, or not drilled. In addition to the Taylor Creek#3 water well, the Colorado Division of Water Resources (DWR) online GIS database shows four deeper water wells constructed in the sub-basin. These are repurposed oil &gas wells which are listed as plugged and abandoned by the COGCC. All other deep wells in the DWR database are outside the northeast flank Piceance Creek sub-basin. Given the lack of identified geologic conduits, the fact that all deeper wells within the area have been plugged and abandoned, and relatively small dispersive fluid front radius (486 ft) determined from the volumetric calculations, a conservative Area of Review(AOR)of 2,640 ft(or one-half mile) is proposed. Attachment A3. Maps The following maps show the nearby wells and the project area geology. • Exhibit A3-1 Deep Wells Map • Exhibit A3-2 Deep Wells Map • Exhibit A3-3 Geologic Map • Exhibit A3-4 Geologic Map UGS I-823 • Exhibit A3-5 Cross Section • Exhibit A3-6 Mine Map Attachment A4.AOR Wells Nearby wells are shown on Exhibits A3-1 and A3-2. The well D-26-A location shown on Exhibits A3- 1 is from the CGS Geologic Map of the Axial Quadrangle, and the report states that the well is 498 feet deep and limited to the Williams Fork Formation. Monitoring wells shown on Exhibits A3-2 are owned by Colowyo and are used to monitor ground water quality at the mine. These wells are completed in the Williams Fork Formation and do not penetrate the confining zone. 3